The present invention relates to an improved process for the handling of fibers during manufacture and subsequent processing and to an improved clip, which clip is particularly suitable for use in the improved process.
It is known in the manufacture of fibers for the manufacturer of the fibers to supply fibers for further processing to their customers in cans or cartons. When the carton or can is full of fiber, the tow or bundle of fibers is cut and the ends are tied in a knot to stop the tow fraying. In use and before further processing, it is generally necessary for the customer to splice the new tow of fiber to a tow currently in use. Because of the knotting of the end of the new tow, the customers have to discard the first 2 to 3 meters of fiber before they have a section suitable for splicing. The discarding of a length of tow each time a new tow is used is clearly undesirable.
It is a particular requirement in the manufacture and subsequent processing of acrylic fiber that the tow of fibers is presented in a form having a rectangular cross-section. The processing of acrylic fiber includes the steps of oxidation and carbonisation, during which process steps the tow is processed at high temperature in a furnace. If the tow frays or does not have a regular rectangular cross-section then any fibers or fiber ends which protrude from the surface of the tow are burnt off in the furnace and the fiber tow is damaged. In the conventional process described above, in which the end of the tow is knotted, it is particularly important to cut off and discard a sufficient length of fiber so that the cut end presents a rectangular cross-section.
It is also known to provide clips for, in particular, the temporary sealing or closing of flexible containers, for example storage bags used in domestic freezers. These clips comprise two substantially straight portions joined at one end by a simple hinge. The free ends of the two substantially straight portions together form a simple hook and clasp mechanism. The two substantially straight portions are profiled in cross-section to provide an array of engaging grooves and ribs which co-operate on closing of the clip over the opening of a flexible container to substantially seal the container and retain any contents therein. Known clips are generally made of plastics material and vary in cross section and length, depending on the size of container with which they are intended to be used.
It is an object of the present invention to provide a novel process for the handling of fibers during manufacture and subsequent processing in which the above disadvantages are reduced or substantially obviated.
It is a further object of the present invention to provide a novel means for preventing fraying of the end of a tow of fibers in which the above disadvantages are reduced or substantially obviated.
The present invention provides a process for the handling of a tow of fibers during manufacture and subsequent processing prior to splicing characterised in that said process includes the step of applying a clip to the free end of said tow, prior to transport of said tow. In a preferred embodiment of the process according to the invention, two clips are applied to the end of said tow, the first close to said free end of said tow and the second spaced along the length of said tow, preferably between 20 and 40 cm from said first clip, more preferably approximately 30 cm from said first clip.
The process according to the invention is of particular application in the handling of carbon fiber precursors, for example acrylic fibers, prior to oxidation and carbonisation to form the carbon fiber.
The present invention further provides a clip for holding an end of a tow of fibers, which clip comprises two substantially straight portions joined at one end by a hinge, the free ends of said two substantially straight portions together forming a clasp mechanism characterised in that the inner surfaces of said two substantially straight portions are flat and smooth along at least part of the length thereof and in that spacing means are provided on said inner surface of at least one of said substantially straight portions of said clip, such that when said clip is closed, said two substantially straight portions are spaced one from the other by a predetermined amount.
In a preferred embodiment of a clip according to the invention, said inner surfaces of said two substantially straight portions are flat and smooth along at least the major part of the length thereof.
In a further preferred embodiment of a clip according to the invention, said spacing means comprise two pairs of projecting pins provided on said inner surface of one of said substantially straight portions of said clip, the first pair being arranged close to said hinge and the second pair being arranged close to said free end of said substantially straight portion.